The present invention is directed to a method wherein a switching device switches data connections in a telecommunication network. A first protocol for signaling control instructions is employed between a control means for controlling the switching device and a first terminal unit.
The switching device, for example, is an exchange of a telephone network or a telecommunication system to which system telephones are connected. An example of a telecommunication system is the system HICOM of Siemens AG. For example, terminal equipment of the type OPTISET are connected to the HICOM. A protocol defined by the manufacturer of the telecommunication system is employed between the control means of the HICOM and the OPTISET terminal equipment, namely the protocol Cornet-TS and Cornet-TC. The terminal units of the OPTISET type are connected to the switching device via an interface unit. However, no protocol conversion is implemented in this interface unit because the signaling protocol defined for the switching device is already matched to the terminal equipment. The connection via such an interface unit is therefore referred to below as direct connection to the switching device.
The telecommunication system relies on the switching device when speech data is transmitted in a voice channel. The switching equipment switches connections between various speech channels over the duration of a conversation. In the simplest case, a voice channel is formed by a line that is only used for a single connection. Analog or digital voice data, without interruption by information for called control, is exchanged via the line. Usually, however, the voice data belonging to different connections is transmitted on a line or on a radio transmission path by time-division multiplex method. A time section within time frames following one another in time is defined for each connection for the transmission of the voice data.
In data transmission networks, too, for example the Internet or an Intranet wherein data are transmitted in data packets, there is switching equipment that forward the data packets in various directions dependent on an identifier in the header of the data packet. A data packet usually contains a number of data words with a predetermined number of bit places, for example what are referred to as octets with eight bit places. In general, octets that belong to the data head can be distinguished in a data packet. In addition to data for indicating the destination of the data packet, for example, the data header also contains data that define, the type of data packet. In addition to the data header, there are usually data words that contain the payload information, for example the voice data. Data words are also transmitted that form an end section of the data packet and, for example, contain a check sum for error recognition and error correction. A separate signaling protocol is specified for the data transmission network.
When connections are to be set up between terminal units that are located in different networks, i.e. for whose operation different signaling protocols are also employed, then a transition means is usually employed between the networks. Such transition means are also referred to as gateways. The gateway makes functions available for all lower layers of what is referred to as the OSI reference model (open systems interconnection), for instance for the bit transmission layer, the security layer, the switching layer and the transport layer. The signaling protocols are also converted in the gateway.
An object of the present invention is to provide a simple method for the operation of a switching device with terminal equipment that works according to different signaling protocols. Moreover, terminal units and systems are provided for implementation of the method.
This object is achieved in accordance with the invention in a method of switching data in a telecommunication network with a switching device. The switching device is controlled by a first control unit. A first protocol signals control commands between a first control unit and a first terminal unit. The first control unit is connected to a second terminal unit via an interface unit. A second protocol different from the first protocol for signaling control commands between the interface unit and the second terminal unit is employed. Control commands are received at the interface unit from the control unit according to the first protocol are embedded into control commands according to the second protocol. The embedded control commands are sent to the second terminal unit. Control commands according to the first protocol from control commands received at the interface unit from the second terminal unit according to the second protocol are sent to said control unit.
The invention proceeds from the consideration that, given employment of the known transmission units, the signaling protocols to each network adjoining the transmission unit must be completely terminated, i.e. that corresponding confirmations in response to demands and corresponding replies in response to messages are to be generated. A complete adaptation of the signaling instructions can only be realized with extremely great outlay. Given employment of the network transition, specific performance features can usually not be used that are exclusively employable in one of the two networks during a signaling.
The present invention is also based on the perception that these problems do not occur when commands according to the signaling protocol of the other network are already generated in a terminal equipment of the one network, and these commands are xe2x80x9ctunneledxe2x80x9d to the switching device, i.e. the commands according to the signaling protocol of the other network are embedded into commands of the signaling protocol of the network wherein the terminal equipment is operated.
In the inventive method, the control unit of the switching device is therefore connected via an interface unit to a second terminal unit. A second protocol that differs from the first protocol is employed for signaling control commands between the interface unit and the second terminal unit. The interface unit embeds control commands received from the control unit according to a first protocol into control commands according to the second signaling protocol and sends this to the second terminal unit. Instead of or in addition to these procedures, the interface unit takes control commands according to a first protocol from the control commands received from the second terminal unit according to the second protocol and sends these to the control unit of the switching device. This means that the control commands according to a first signaling protocol had been previously embedded into signaling commands according to the second protocol in the second terminal equipment.
What the tunneling achieves is that, given specific changes of the first signaling protocol, no modifications need be undertaken in the interface unit. For example, a new command word can be determined without modification of the interface unit that the interface unit embeds together with the previously employed command words in control commands according to the second signaling protocol or that are taken from control commands according to the second signaling protocol. Modifications are only to be implemented in the switching device and in the terminal equipment.
What the tunneling also achieves is that the switching device control, the terminal unit or the terminal unit controls the exchange in network-overlapping fashion in the manner of a hidden remote control. The performance features of the switching equipment can thereby be completely used in the signaling between terminal unit and switching equipment.
The interface unit given the inventive method is driven by the switching device in the same way as the first terminal unit. The interface unit also signals to the switching device in the same way as the first terminal equipment. Modifications in the switching device are therefore not required given connection of the interface unit. In the direction toward the second terminal unit, by contrast, the interface unit looks like a terminal unit of the data transmission network in which signaling is carried out according to the second signaling protocol.
In an embodiment, the first protocol is a stimulus protocol with whose assistance statuses of operating elements of a terminal unit are reported to the control unit and/or with whose assistance statuses of signal elements of a terminal unit can be set by the control unit. The terminal equipment thus requires no information about call, control and type of performance features. The performance features are defined in the switching device. The terminal units can thus be simply constructed. What is achieved by the tunneling is that performance features defined network-specifically can also be completely utilized proceeding from another network.
In an embodiment, the second protocol is a functional protocol that, dependent on a function selected in a terminal unit or on a function to be carried out by a terminal unit, requires a command defined for this function. In this case, a special command of the functional protocol is defined for the tunneling. With this command, commands according to stimulus protocol or according to some other functional protocol are tunneled in the interface unit.
In an embodiment, the transmitted commands are searched in the interface unit for commands that require the setup or the cleardown of a payload data connection between the switching device and the second terminal unit. Given the occurrence of a sought command, the interface unit initiates the setup or the cleardown of the payload data connection.
This last embodiment is based on the consideration that the interface unit is to work in the direction toward the switching device like a first terminal equipment, i.e. a terminal equipment directly connectable to the switching device. In the direction toward the second terminal unit, the interface unit should work exactly like a terminal unit of the second network. This can be achieved when, in addition to the signaling protocol, the payload data connection is also processed in the interface unit. The setup or cleardown of the payload data connection is usually implemented by hardware in the switching device. This hardware, however, cannot be used for the setup of a payload data connection to another network. The interface unit therefore assumes this job.
The same method steps as for a connection to the first terminal unit are implemented in the switching device for the signaling and the payload data connection to the second terminal equipment. Additional method steps need not be carried out. What is thus achieved is that no additional resources are required in the switching device given a connection to a second terminal unit compared to a connection to the first terminal unit, i.e. no additional signaling connections and no additional payload data connections. The switching device can thus be used for a number of connections to terminal units that work according to the second signaling protocol.
When, given an embodiment in the interface unit, data transmitted by the switching device in a data channel is distributed onto data packets and is transmitted to this terminal unit according to a transmission protocol defined for the second terminal unit, then the interface unit is an interface between a data transmission network, wherein the data is transmitted in voice channels, and a data transmission network, wherein the data is transmitted in data packets. In the other direction, data packets coming from the second terminal equipment are unpacked in the interface, and the unpacked data are forwarded to the switching device in a data channel. The transmission of data in a data channel is employed, in particular, for the transmission of voice data because voice data use, a voice channel well. By employing the interface unit, the voice data, however, can also be transmitted in data transmission networks wherein data other then voice data is mainly communicated, for example document data files, program data files or table calculation data files.
In an embodiment, the inventive method is utilized for a second terminal unit that works according to ITU standard (International Telecommunication Union) H.323 xe2x80x9cPacked-Based-Mutlimedia Communication Systemsxe2x80x9d. In this case, performance features of the switching device can be used in the second terminal unit without greater outlay. One need not wait until standards based on the standard H.323 have been developed for these performance features. See, for example, Standard H.450.1 xe2x80x9cGeneric Functional Protocol for the support of supplementary services in H.323xe2x80x9d and Standard H.450.2 ff.
The present invention is also directed to an interface unit that is suitable for the implementation of the inventive method or the embodiments thereof. In particular, the inventive interface unit is utilized in a switching device. Further, the present invention is directed to a program for the execution of the inventive method or the embodiments thereof. The technical effects cited above for the inventive method and the embodiments thereof also apply to the interface unit, the switching device and the program.
The present invention is also directed to a method comprising the method steps of transmitting control commands in a signaling unit of a second terminal unit according to a first signaling protocol being employed between a switching device and a first terminal unit directly connected to said switching equipment; transmitting control commands at a connection of said signaling unit connected to a data transmission network according to a second signaling protocol different than said first signaling protocol; embedding control commands generated in said signaling unit by said second terminal unit according to said first signaling protocol in control commands according to said second signaling protocol; sending said embedded control commands to said first terminal unit; receiving control commands according to said first signaling protocol in said signaling unit from control commands according to said second signaling protocol received at said terminal; and processing said received control commands in said second terminal unit.
These method steps relate to the second terminal unit and are closely technologically related to the method steps of the first-cited inventive method. The technical effects cited above for the first inventive method and the developments thereof thus also apply to the second inventive method. The present invention is also directed to a terminal unit and to a program that are suitable for the implementation of the second inventive method.